The name Ploutōn was frequently conflated with that of Plutus (Πλοῦτος, Ploutos), a god of wealth, because mineral wealth was found underground, and because as a chthonic god Pluto ruled the deep earth that contained the seeds necessary for a bountiful harvest. Ploutōn became a more positive way to talk about the ruler of the underworld, and the name was popularized through the mystery religions and philosophical systems influenced by Plato, the major Greek source on its meaning.